The present invention relates generally to modular electrical connector assemblies for use in the transmission of high frequency signals and more specifically to multi-port, multi-level connector assembly.
Data communication networks are being developed which enable the flow of information to ever greater numbers of users at ever higher transmission rates. However, data transmitted at high rates in multi-pair data communication cables has an increased susceptibility to crosstalk, which often adversely affects the processing and integrity of the transmitted data. The problem of crosstalk in information networks increases as the frequency of the transmitted signals increases.
In the case of local area network (LAN) systems employing electrically distinct twisted wire pairs, crosstalk occurs when signal energy inadvertently xe2x80x9ccrossesxe2x80x9d from one signal pair to another. The point at which the signal crosses or couples from one set of wires to another may be 1) within the connector or internal circuitry of the transmitting station, referred to as xe2x80x9cnear-endxe2x80x9d crosstalk, 2) within the connector or internal circuitry of the receiving station, referred to as xe2x80x9cfar-end crosstalkxe2x80x9d, or 3) within the interconnecting cable.
Near-end crosstalk (xe2x80x9cNEXTxe2x80x9d) is especially troublesome in the case of telecommunication connectors of the type specified in sub-part F of FCC part 68.500, commonly referred to as modular connectors. Such modular connectors include modular plugs and modular jacks. The EIA/TIA of ANSI has promulgated electrical specifications for near-end crosstalk isolation in network connectors to ensure that the connectors themselves do not compromise the overall performance of the unshielded twisted pair interconnect hardware typically used in LAN systems. The EIA/TIA Category 5 electrical specifications specify the minimum near-end crosstalk isolation for connectors used in 100 ohm unshielded twisted pair Ethernet type interconnects at speeds of up to 100 MHz.
High speed data transmission cable typically comprise four circuits defined by eight wires arranged in four twisted pairs. The cable is typically terminated by modular plugs having eight contacts, and specified ones of the four pairs of the plug contacts are assigned to terminate respective specified ones of the four cable wire pairs according to ANSI/EIA/TIA standard 568B. The four pairs of plug contacts in turn engage four corresponding pairs of jack contacts. In particular, the standard 568B contact assignment for the wire pair designated xe2x80x9c1xe2x80x9d is the pair of plug and jack contacts located at the 4-5 contact positions. The cable wires of the pair designated xe2x80x9c3xe2x80x9d are, according to standard 568, terminated by the plug and jack contacts located at the 3-6 positions which straddle the xe2x80x9c4-5xe2x80x9d plug and jack contacts that terminate wire pair xe2x80x9c1xe2x80x9d. Near-end crosstalk between wire pairs xe2x80x9c1xe2x80x9d and xe2x80x9c3xe2x80x9d during high speed data transmission has been found to be particularly troublesome in connectors that terminate cable according to standard 568.
While it is desirable to use modular connectors for data transmission for reasons of economy, convenience and standardization, such connectors generally comprise a plurality of identically configured electrical contact/terminal members that extend parallel and closely spaced to each other thereby creating the possibility of excessive near-end crosstalk at high frequencies. Specifically, modular jacks generally include a plurality of unitary contact/terminal members made of conductive material and formed to provide a corresponding plurality of closely spaced, substantially parallel contact portions which are adapted to be engaged by blade-like contacts of the modular plugs. Each contact/terminal member is formed to further provide a pin-like terminal portion and an intermediate portion interconnecting the contact and terminal portions. The terminal portion can be connected to the circuit of a printed circuit board. When a modular plug is inserted into the receptacle of a modular jack, the contact blades of the plug engage respective contact portions of the contact/terminal members of the jack. The signals flowing through the contact/terminal members of each transmission circuit create electromagnetic and inductive fields which undesirably couple to other circuits resulting in near-end crosstalk.
Since it has been appreciated that the identical configuration of the contact/terminal members causes crosstalk, several fundamentally different techniques have been developed to vary the shape of the contact/terminal members and thereby reduce crosstalk. A first technique, exemplified by U.S. Pat. Nos. 5,639,266 and 5,791,942 (Patel), incorporated by reference herein, is to form the contact/terminal members so that selective contact portions are forward facing while others are rearward facing while maintaining the contact/terminal members substantially parallel to one another. More particularly, the connector described in the ""266 patent includes a contact/terminal member having a contact portion having a free end situated near and facing toward a front of the receptacle (xe2x80x9ca forward facing contact portionxe2x80x9d), and a contact/terminal member having a contact portion having a free end situated near and facing toward the closed end of the receptacle (xe2x80x9ca rearward facing contact portionxe2x80x9d) whereby the contact/terminal member with the forward facing contact portion inherently has a different shape than the contact/terminal member with the rearward facing contact portion. Crosstalk is reduced by virtue of the different geometry of the contact/terminal members.
A second technique is to construct the contact/terminal members to physically cross-over one another and is exemplified by U.S. Pat. No. 5,362,257 (Neal et al.). In the ""257 patent, each contact/terminal member is arranged to cross-over an adjacent contact/terminal member at least once to thereby reduce near-end crosstalk.
Furthermore, as the size of electronic components has become reduced with advances in semiconductor technology, it has become increasingly necessary to increase the number of modular connector ports which can be mounted within a given area.
Accordingly, it is an object of the present invention to provide new and improved connector assemblies for use in data transmission at high frequencies.
Another object of the present invention is to provide new and improved high frequency modular connector assemblies which reduce near-end crosstalk during data transmission.
Still another object of the present invention is to provide new and improved modular connector assemblies for use in Category 5 applications which reduce near-end crosstalk during data transmission.
A still further object of the present invention is to provide new and improved high frequency multi-port, multi-level connector assemblies which reduce near-end crosstalk during data transmission.
Yet another object of the present invention is to provide new and improved modular connector assemblies which provide reduced near-end crosstalk when connected to modular plugs that terminate high speed data transmission cable according to ANSI/EIA/TIA standard 568.
Another object of the invention is to provide new and improved modular connector assemblies in which each contact/terminal member has a different geometry than the contact/terminal member(s) adjacent thereto in order to inhibit the occurrence of near-end crosstalk when adjacent contact/terminal members have essentially the same geometry.
Still another object of the invention is to provide a new and improved insert assembly for mating with an outer housing part to form a plug-receiving receptacle of a jack.
Briefly, these and other objects are attained by modifying the standard construction of modular connector assemblies, which generally comprise a plurality of identically configured contact/terminal members, by providing at least two geometrically different contact/terminal members arranged in the connector assembly so that each contact/terminal member is different than the contact/terminal member(s) adjacent thereto. The connector assembly includes a jack and an optional shield. By geometrically different, it is meant that the contact/terminal members do not have the same overall shape, regardless of the dimensions thereof. To this end, a connector insert assembly is arranged in the jack housing and includes a set of a first form of unitary contact/terminal members, each including a contact portion extending into a plug-receiving receptacle defined in the jack housing, a terminal portion extending beyond a bottom surface of the insert assembly so as to enable electrical connection to a circuit of a printed circuit board, and an intermediate portion interconnecting the contact portion and the terminal portion, and a set of a second form of unitary contact/terminal members, each including a contact portion extending into the receptacle, a terminal portion extending beyond the bottom surface of the insert assembly and an intermediate portion interconnecting the contact portion and the terminal portion. The contact/terminal members in the first set are substantially parallel to and geometrically different from the contact/terminal members in the second set, and the contact/terminal members are positioned in an insert housing of the insert assembly such that each contact/terminal member is different from any adjacent contact/terminal member(s).
When providing geometrically different contact/terminal members arranged substantially parallel to one another, it is desirable to space or distance the contact/terminal members from one another as much as possible, this separation between the contact/terminal members resulting in a reduction in crosstalk between the contact/terminal members. In a preferred embodiment, this is achieved by spacing at least a portion of the conductor portion of each contact/terminal member in the first set from an opposed conductor portion of each contact/terminal member in the second set, while maintaining the generally parallel arrangement of contact/terminal members, i.e., the contact/terminal members in the first and second sets do not cross over one another. For example, the conductor portion of the contact/terminal members in the first set may be situated in a first horizontal plane and at least a portion of the conductor portion of the contact/terminal members in the second set is situated in a second horizontal plane vertically spaced from the first horizontal plane. Thus, at a minimum, the conductor portion of each contact/terminal member in the first set is different than the conductor portion of each contact/terminal member in the second set.
By contrast, the identically configured contact/terminal members in a conventional prior art connector may have the same geometric shape and possibly differ only with respect to the length of the conductor portion, i.e., to allow for terminal portions of the contact/terminal members to be situated in two rows. This difference in length does not provide any vertical separation of the conductor portions of the contact/terminal members.
To accommodate the different contact/terminal members in the insert housing, in an embodiment wherein the receptacle is defined above a top surface of the insert assembly, the insert housing defines first and second sets of conduits, the conduits in each set are the same but the conduits in the first set are different than the conduits in the second set. The conduits in the first set each receive a respective one of the contact/terminal members of the first set and the conduits in the second set each receive a respective one of the contact/terminal members of the second set. The first and second sets of conduits are defined in the insert housing such that adjacent contact/terminal members are different from one another.
In a preferred embodiment, the insert includes a third set of contact/terminal members substantially parallel to the contact/terminal members in the first and second sets and each including a contact portion extending into the receptacle, a terminal portion extending beyond the bottom surface of the insert assembly and an intermediate portion interconnecting the contact portion and the terminal portion. The contact/terminal members in the third set are geometrically different than the contact/terminal members in the first and second sets. The insert housing also includes a third set of conduits which are different than the conduits in the first and second sets of conduits. Each conduit in the third set of conduits receives a respective one of the contact/terminal members of the third set of contact/terminal members. The first, second and third sets of conduits are arranged such that each contact/terminal member is different from any adjacent contact/terminal member(s).
In another preferred embodiment, the contact portion of each contact/terminal member in the first set is inclined and has a free edge facing a rear of the insert housing such that the contact/terminal members in the first set provide a xe2x80x9crearward facing contact portionxe2x80x9d. The contact portion of each contact/terminal member in the second set is also inclined but has a free edge facing a front of the insert housing such that the contact/terminal members in the second set provide a xe2x80x9cforward facing contact portionxe2x80x9d. The contact/terminal members in the third set, if present, may be constructed to provide either a forward facing or rearward facing contact portion. By positioning a contact/terminal member having a forward facing portion adjacent a contact/terminal member having a rearward facing contact portion, crosstalk is reduced as discussed in the Patel patents referenced above, in addition to the reduction in crosstalk obtained by virtue of the different geometry of the contact/terminal member having a forward facing portion and the contact/terminal member having a rearward facing contact portion.
In accordance with the invention, the insert assembly may include a minimum of two geometrically different contact/terminal members, e.g., from only two different sets of contact/terminal members, or three or more geometrically different contact/terminal members, and which are arranged so that each contact/terminal member is different from any adjacent contact/terminal member(s). If contact/terminal members from only two sets of geometrically different contact/terminal members are used in a connector in accordance with the invention, then the contact/terminal members must be arranged in an alternating pattern. If contact/terminal members from three or more sets of geometrically different contact/terminal members are used in a connector in accordance with the invention, then the number of contact/terminal members from each set may be selected as desired and the contact/terminal members arranged in any desired manner so long as each contact/terminal member is geometrically different from any adjacent contact/terminal member(s).
Preferably, in an eight position, eight contact jack, the contact/terminal members at positions P3 and P5 are contact/terminal members having a forward facing contact portion whereas the contact/terminal members at positions P1, P2, P4, P6, P7 and P8 are contact/terminal members having a rearward facing contact portion. In order to avoid having adjacent contact/terminal members with the same geometry, the contact/terminal members having a rearward facing contact portion at positions P2, P4, P6 and P8 are geometrically different than the contact/terminal members at positions P1 and P7, i.e., from different sets of contact/terminal members.
Any geometrical configurations of contact/terminal members may be used in the invention, which may include either a forward facing contact portion or a rearward facing contact portion, as well as contact/terminal members which cross-over one another. It is important though that in order to reduce crosstalk between the contact/terminal members in the connector in accordance with the invention, each contact/terminal member should be geometrically different from any adjacent contact/terminal member(s), i.e., has a different shape therefrom. This is so at least for the contact/terminal member(s) which are most susceptible to crosstalk. It is thus recognized that some of the contact/terminal members may have the same geometrical configuration as an adjacent contact/terminal member if it is found that providing the adjacent contact/terminal members with different geometrical configurations does not meaningfully reduce crosstalk.
In a still further preferred embodiment the insert housing is constructed as a unitary member made as a single component, in contrast to certain above-described embodiments which consist of three elements formed into the insert housing. This component is made typically by injection molding of a suitable plastic. One advantage of this one-piece member is that it will substitute for the manufacture and assembly of three sub-components to form such housing insert. This new insert housing includes structure to receive and securely retain a plurality of contact/terminals, each of which is geometrically different from the ones immediately adjacent thereto. All the geometric configurations of contact/terminals and arrangements of first, second and/or third sets of contact/terminals mounted to an insert housing, as described earlier herein, are applicable to this one-piece member. Also, other structural features of the previously described insert housings such as guides and latches for coupling to the connector housing may be employed.
In another preferred embodiment, the insert housing is substantially L-shaped and generally comprises a base part having top and bottom surfaces, front and rear surfaces and opposed lateral surfaces, and a cap part separable from the base part and having top and bottom surfaces, front and rear surfaces and opposed lateral surfaces. The bottom surface of the cap part partially overlies the top surface of the base part such that the cap part extends in a cantilever fashion from the base part. The conduits in the first, second and third sets of conduits are formed in connection with both the base part and the cap part.
The multi-port, multi-level connector assembly for receiving multiple plugs in accordance with the invention which makes use of the insert assembly in any of the embodiments described above includes a jack comprising an outer housing part defining a plurality of receptacles arranged in an upper and lower level, each including at least one receptacle receivable of a respective plug, at least one lower insert assembly arranged in the outer housing part and including a plurality of contact/terminal members which engage contacts on a respective plug upon insertion thereof into a respective receptacle in the lower level, and at least one upper insert assembly arranged in the outer housing part and including a plurality of contact/terminal members which engage contacts on a respective plug upon insertion thereof into a respective receptacle in the upper level. The upper insert assembly is as in any of the embodiments described above.
When used herein, a contact/terminal member includes a contact portion situated in the plug-receiving receptacle, a terminal portion for connection to a substrate and an intermediate or bridging portion connecting the contact portion to the terminal portion. However, when the contact/terminal member is not critical to an embodiment of the invention, instead of a contact/terminal member, an assembly of a contact situated at least partially in the receptacle, a terminal situated at least partially below the lower surface or beyond the rear surface of the connector for connection to a substrate and some other intermediate structure for interconnecting the contact and terminal may be used, e.g., a printed circuit board having a wiring pattern. For example, this would be the case for the multi-level connector assembly described herein wherein the lower insert assembly is not required to include contact/terminal members but may include separate contacts and terminals.